1. Field of the Invention
The present invention relates generally to image processing. More particularly, the present invention relates to differentiating images.
2. Background Art
To enhance the entertainment value and enjoyment of amusement venues and other applications, it is often advantageous to provide content tailored to unique interests or characteristics of individuals or small groups. By providing content that leverages subject recognition features, highly personal interactions can be provided, customized to suit individual tastes and preferences. For example, the facial features of a user might be recognized and superimposed over the user's favorite character and printed as a souvenir, providing highly personal and lasting memories.
To provide these personalization features, the subjects of interest must often be isolated from other objects or background elements that may interfere with downstream image recognition and manipulation. Generally, this background removal process requires some level of control over the environment, so that a background having no subjects can be accurately modeled for comparing against a background including some subjects of interest. Furthermore, this process can be expedited by keeping the background static and hued differently from the predominant hues of the subjects.
The “blue-screen” and “green-screen” chroma key techniques are examples of such background removal processes. Since green or blue hues are rarely seen in natural skin pigments, they are often ideal hues for chroma key. By isolating only the subjects of interest, such as actors in motion pictures or weather anchors in news broadcasts, a more interesting background can be substituted, such as a computer generated background for a movie, or an animated weather map for a weather report. Moreover, multiple subjects can be assembled in a single scene, and other flexible transformations can provide interesting and compelling effects. For example, a common application is the modern digital photo booth seen in amusement settings. These photo booths can leverage chroma key techniques in a carefully controlled and enclosed environment to provide users with personalized prints or stickers with fun and decorative composited backgrounds.
Thus, for effective use of background removal techniques such as chroma key, the environment around the subjects usually requires a high degree of control and regulation. For example, the area behind the subjects of interest must typically include a painted wall or some other structure to provide a color hue matching a particular chroma key technique being used, and lighting must be carefully managed to avoid jarring shadow artifacts or other anomalies. In addition, since chroma key techniques are typically used in conjunction with video capture providing only two-dimensional image frames, subject distances or depth relative to a camera must be typically determined in advance and strictly regulated, or special markers must be physically inserted into the scene area to act as scaling guideposts. Otherwise, improper spatial attribution for subjects or incorrect subject scaling may occur at the composition stage.
However, in an amusement park or other public venue, particularly where many people may be situated close together, possibly without strict placement control, it may be difficult to determine subject depth correctly. The additional variables of subject ages, heights, and body compositions may further confound attempts at estimating subject depth from two-dimensional images provided by standard video cameras. Thus, due to many practical difficulties in arranging a suitable working environment, traditional background removal techniques such as chroma key have seen limited opportunities for deployment in public settings, even though tremendous benefits can be realized in the form of personalization and other enabled effects.
Accordingly, there is a need to overcome the drawbacks and deficiencies in the art by providing a way to achieve the results of blue or green screen chroma key techniques for depth sensitive subject isolation from backgrounds without requiring a traditional chroma key environmental setup.